Reservoir monitoring, sometimes referred to as reservoir surveillance, involves the regular collection and monitoring of measured production data from within and around the wells of a reservoir. Such data may include, but is not limited to, water saturation, water and oil cuts, fluid pressure and fluid flow rates. As the data is collected, it is archived into a historical database.
The collected production data, however, mostly reflects conditions immediately around the reservoir wells. Simulations model the overall behavior of the entire reservoir based on the collected data, both current and historical, to provide a more complete picture of the state of a reservoir. These simulations produce simulated interwell data values both near and at a distance from the wellbores. Simulated near-wellbore data is correlated against measured near-wellbore data, and the modeling parameters are adjusted as needed to reduce the error between the simulated and measured data. Once so adjusted, the simulated interwell data, both near and at a distance from the wellbore, may be relied upon to assess the overall state of the reservoir. Such data may also be relied upon to predict the future behavior of the reservoir based upon either actual or hypothetical conditions input by an operator of the simulator.
The results of such predictive simulations may be used to determine optimal settings for operating the wells within the reservoirs and thus maximize reservoir production. However, these settings are typically optimized for each well individually. For reservoirs with multiple wells feeding a common gathering network that delivers the product to a single processing facility, the well-optimized solution can result in violations of processing facility constraints. For example, for wells that are oil rate constrained, the water rate may increase over time such that the overall water rate may exceed the processing facility's maximum water limit. If this violation exceeds a pre-established tolerance, additional simulation iterations are generally performed to determine updated well-optimized operating parameters. Such additional simulations can incur significant additional operating costs, given that reservoir simulations, particularly those that perform full physics numerical simulations of large reservoirs, are computationally intensive and can take hours, even days to execute.
It should be understood that the drawings and corresponding detailed description do not limit the disclosure, but on the contrary, they provide the foundation for understanding all modifications, equivalents, and alternatives falling within the scope of the appended claims.